Memory Test Research Articles

Retelling of Stories with Common Phrasal Expressions by High-Proficiency Learners: Implications for Learning and High-Stakes Testing

The goal of this research was to investigate how well L2 English speakers of different proficiency levels were able to perform on a test of auditory memory like that used in the Wechsler Memory Scale (WMS). In this test, participants must retell heard stories. While the validity of elicited imitation tests is well established in second-language acquisition research, the effectiveness of using retelling as a neuropsychological measurement when a language other than the test taker’s L1 is used is unclear. Further, due to their importance in memory function, this study also analyzed the role of common phrasal expressions in how well participants retold stories in three groups of different proficiency. The results indicated that the increase in scores in the retelling of stories aligned with the proficiency level of the non-native participants. Higher-proficiency NNSs were also able to use more of the commonly used spoken phrases in their retelling. Further, there was no difference in this measure between the higher-proficiency Second-Language English and First-Language English participants. While the effectiveness of this test method as a neuropsychological tool when a language other than the test taker’s L1 is used is unclear, these results indicate significant progress by the higher-proficiency participants. Nevertheless, given that this test is often used in this context with immigrants and minority language patients, doubts remain about its suitability for less proficient individuals.

Impact of Neuropsychological Assessment on Subjective Memory Complaints in Patients With Mild Cognitive Impairment.

Patients with Alzheimer's disease (AD), namely at an initial stage like amnestic cognitive impairment (aMCI), typically present with memory complaints. They also have difficulties regarding self-knowledge about their cognitive deficits. In clinical practice, a formal neuropsychological assessment is often done. The present study aimed to understand whether patients with aMCI retain the ability to monitor the success or failure in their performance during the neuropsychological assessment and adjust the report of memory complaints accordingly, as compared to healthy controls. Participants were patients with aMCI and healthy controls who were questioned about their own memory abilities using the Subjective Memory Complaints (SMC) scale, applied before and after the neuropsychological assessment protocol. A repeated measures General Linear Model was performed to analyze changes in SMC (within-subjects effects) after the neuropsychological assessment, in patients with aMCI and healthy controls (between-subjects effects). Eighty volunteers, 40 patients with aMCI and 40 healthy controls, participated in the study. Patients with aMCI showed lower MMSE scores, more depressive symptoms, and deficits in memory and learning, language and executive domains. Patients with aMCI had higher SMC scores [9.4(3.6)] than healthy controls [4.4(2.3)] before the neuropsychological assessment. A statistically significant interaction was found between the SMC and the diagnostic group, meaning that healthy controls decreased SMC [3.4(1.9)] after the neuropsychological assessment, whereas patients with aMCI kept high levels of SMC [9.6(3.9)]. In patients with aMCI, an inverse correlation between logical memory and the change in SMC was found, so that patients with lower scores in the logical memory test tended to increase their memory complaints after the assessment. Both patients with aMCI and healthy controls can monitor and update the impression about their memory abilities following a formal neuropsychological assessment. Patients with aMCI maintain a high SMC level, which is inversely associated with their memory performance. In practical terms, SMC should be measured consistently at a particular moment in time, preferably preceding the objective neuropsychological assessment.

Social-semantic knowledge in frontotemporal dementia and after anterior temporal lobe resection

Abstract Degraded semantic memory is a prominent feature of frontotemporal dementia (FTD). It is classically associated with semantic dementia and anterior temporal lobe (ATL) atrophy, but semantic knowledge can also be compromised in behavioural-variant FTD (bvFTD). Motivated by understanding behavioural change in FTD, recent research has focused selectively on social-semantic knowledge, with proposals that the right ATL is specialised for social concepts. Previous studies have assessed very different types of social concepts and have not compared performance to that on matched non-social concepts. Consequently, it remains unclear to what extent various social concepts are (i) concurrently impaired in FTD, (ii) distinct from general semantic memory and (iii) differentially supported by the left and right ATL. This study assessed multiple aspects of social-semantic knowledge and general conceptual knowledge across cohorts with ATL-damage arising from either neurodegeneration or resection. We assembled a test battery measuring knowledge of multiple types of social concept. Performance was compared to non-social general conceptual knowledge, measured using the Cambridge Semantic Memory Test Battery and other matched non-social-semantic tests. Our transdiagnostic approach included bvFTD, semantic dementia and “mixed” intermediate cases to capture the FTD clinical spectrum, as well as age-matched healthy controls. People with unilateral left or right ATL resection for temporal lobe epilepsy (TLE) were also recruited to assess how selective damage to the left or right ATL impacts social- and non-social-semantic knowledge. Social- and non-social-semantic deficits were severe and highly correlated in FTD. Much milder impairments were found after unilateral ATL resection, with no left vs. right differences in social-semantic knowledge or general semantic processing, and with only naming showing a greater deficit following left vs. right damage. A principal component analysis of all behavioural measures in the FTD cohort extracted three components, interpreted as capturing: (1) FTD severity, (2) semantic memory and (3) executive function. Social and non-social measures both loaded heavily on the same semantic memory component, and scores on this factor were uniquely associated with bilateral ATL grey matter volume but not with the degree of ATL asymmetry. Together, these findings demonstrate that both social- and non-social-semantic knowledge degrade in FTD (semantic dementia and bvFTD) following bilateral ATL atrophy. We propose that social-semantic knowledge is part of a broader conceptual system underpinned by a bilaterally-implemented, functionally-unitary semantic hub in the ATLs. Our results also highlight the value of a transdiagnostic approach for investigating the neuroanatomical underpinnings of cognitive deficits in FTD.

Decoding episodic autobiographical memory in naturalistic virtual reality

Episodic autobiographical memory (EAM) is a long-term memory system of personally experienced events with their context – what, where, when – and subjective elements, e.g., emotions, thoughts, or self-reference. EAM formation has rarely been studied in a controlled, real-life-like paradigm, and there is no predictive model of long-term retrieval from self-rated subjective experience at encoding. The present longitudinal study, with three surprise free recall memory tests immediately, one-week and one-month after encoding, investigated incidental encoding of EAM in an immersive virtual environment where 30 participants either interacted with or observed specific events of varying emotional valences with simultaneous physiological recordings. The predictive analyses highlight the temporal dynamics of the predictors of EAM from subjective ratings at encoding: common characteristics related to sense of remembering and infrequency of real-life encounter of the event were identified over time, but different variables become relevant at different time points, such as the emotion and mental imagery or prospective aspects. This dynamic and time-dependent role of memory predictors challenges traditional views of a uniform influence of encoding factors over time. Current evidence for the multiphasic nature of memory formation points to the role of different mechanisms at play during encoding but also consolidation and subsequent retrieval.

Single Strength Training Session Improves Short-Term Memory in Cognitively Preserved Older Adults.

The purpose of the present study was to examine the acute effect of a single aerobic or strength training session on memory of cognitively preserved older adults. In this randomized controlled clinical trial, in the first visit the participants (52.2% men, aged 68.65 ± 2.81years-old, BMI 26.94 ± 4.09), were randomly allocated in one of three groups: AG (aerobic exercise group), SG (strength exercise group, submitted to five exercises with 15 repetitions each), and CG (control group). Participants had a short-term memory assessment (word list memory test) followed by a single exercise session, and were retested immediately after. 24h later, participants were submitted to a long-term memory assessment about the story that was presented in the previous day. Results showed that the SG group had a significant improvement in the word list test, when comparing pre- and post-intervention scores, suggesting that a single strength training session significantly enhances short-term memory in this population.

Ghrelin for Neuroprotection in Post-Cardiac Arrest Coma: a one-year follow-up of cognitive and psychosocial outcomes.

Effective treatments to improve brain recovery after cardiac arrest are needed. Ghrelin showed efficacy in experimental models and was associated with lower neuron specific enolase levels in the clinical Ghrelin in Coma (GRECO) trial. Here we present cognitive and psychosocial outcomes at one-year follow-up. GRECO was a phase 2 multicenter, double-blind, randomized, placebo-controlled trial in comatose patients after cardiac arrest. The intervention was intravenous acyl-ghrelin 600 μg twice daily or placebo for one week, starting within 12 hours after the arrest. Patients were assessed after one year using cognitive tests and questionnaires measuring participation, health-related quality of life, mood, and caregiver strain. Composite z-scores of the cognitive tests were computed by comparing the scores to those of a norm-population and averaging the tests for memory, attention and executive functioning separately. Groups were compared based on composite z-scores and cutoff scores for psychosocial outcomes. Of the 160 participants originally included, 66 of the 85 participants who survived to one year after OHCA completed the psychosocial and cognitive follow-up. The intervention group scored numerically higher across all cognitive domains compared to the control group, but the differences were not statistically significant (memory median = -.850 vs. -1.385, U = 424.5, p = .587; attention median = -.733 vs. -.717, U = 420.5, p = .548; executive functioning median = -.311 vs. -.369, U = 408.5, p = .323). There were significantly fewer signs of depression in the intervention group, U = 322.5, p = .014. This predefined secondary analysis found that ghrelin treatment was associated with non-significantly but consistently better cognitive outcomes and significantly fewer signs of depression. This is in line with the primary outcomes. Clinicaltrialsregister.eu: EUCTR2018-000005-23-NL.

Different dorsolateral prefrontal activation during an emotionalautobiographical memory task between male and female depressed individuals: a fNIRS study.

Depression in male and female are commonly associated with different prevalence, severity, and, in some cases, distinct syndromes or subtypes. However, only a small amount of research has been conducted to completely understand the underlying neuroanatomical mechanisms. The goal of the current study was to provide neural markers for specific depression therapies by demonstrating the differences in aberrant prefrontal activity between male and female depressed subjects during an emotional autobiographical memory test. The study included 127 young adults who were randomly assigned to one of two groups: male depression (62 participants) or female depression (65 participants). The average oxyhemoglobin levels in the dorsolateral prefrontal cortex throughout the emotional autobiographical memory task were assessed utilizing 53-channel functional near-infrared spectroscopy imaging equipment. The oxy-Hb activation in the left dorsolateral prefrontal cortex (lDLPFC) and right dorsolateral prefrontal cortex (rDLPFC) had no significant interaction between groups and emotional valences. A significant main effect was found between male and female, with female depression groups showing lower oxy-Hb activity in lDLPFC and rDLPFC than male depression groups. Male and female depression patients showed distinct brain activation in the DLPFC during an emotional autobiographical memory test, suggesting potential specific neurological indicators for varied somatic symptoms in male and female depression patients. These distinctions should be taken into account while creating preventive measures.

Does working memory training in children need to be adaptive? A randomized controlled trial.

Most cognitive training programs are adaptive, despite limited direct evidence that this maximizes children's outcomes. This randomized controlled trial evaluated working memory training with difficulty of activities presented using adaptive, self-select, or stepwise compared with an active control. At baseline, immediately, and 6-months post-intervention, 201 Australian primary school children (101 males, 7-11 years) completed working memory tests (near and intermediate transfer) and the Raven's Standard Progressive Matrices, and caregivers completed the attention-deficit/hyperactivity disorder-Rating Scale-5 (far transfer). The intervention comprised ten 20-min sessions delivered in class. For each training condition, compared with the active control, there was no evidence of transfer immediately or 6-months post-intervention (negligible to small effects). This trial provides no evidence that adaptive working memory training maximizes children's outcomes.

Exploring the links among brain iron accumulation, cognitive performance, and dietary intake in older adults: A longitudinal MRI study

This study evaluated longitudinal brain iron accumulation in older adults, its association with cognition, and the role of specific nutrients in mitigating iron accumulation. MRI-based, quantitative susceptibility mapping estimates of brain iron concentration were acquired from seventy-two healthy older adults (47 women, ages 60–86) at a baseline timepoint (TP1) and a follow-up timepoint (TP2) 2.5–3.0 years later. Dietary intake was evaluated at baseline using a validated questionnaire. Cognitive performance was assessed at TP2 using the uniform data set (Version 3) neuropsychological tests of episodic memory (MEM) and executive function (EF). Voxel-wise, linear mixed-effects models, adjusted for longitudinal gray matter volume alterations, age, and several non-dietary lifestyle factors revealed brain iron accumulation in multiple subcortical and cortical brain regions, which was negatively associated with both MEM and EF performance at T2. However, consumption of specific dietary nutrients at TP1 was associated with reduced brain iron accumulation. Our study provides a map of brain regions showing iron accumulation in older adults over a short 2.5-year follow-up and indicates that certain dietary nutrients may slow brain iron accumulation.

Post-stroke fatigue severity is associated with executive dysfunction in chronic stroke

ABSTRACT Following stroke, fatigue is highly prevalent and managing fatigue is consistently rated a key unmet need by stroke survivors and professionals. Domain-specific cognitive impairments have been associated with greater fatigue severity in earlier stages of stroke recovery, but it is unclear whether these associations hold in chronic (>2 years) stroke. The present cross-sectional observational study evaluates the relationship between domain-specific cognitive functioning and the severity of self-reported fatigue among chronic stroke survivors. Participants (N = 105; mean age = 72.92, 41.90% female; mean years post-stroke = 4.57) were assessed in domains of attention (Hearts Cancellation test), language (Boston Naming Test), episodic memory (Logical Memory Test), working memory (Digit Span Backwards task), and executive functioning (set-shifting: Trail Making Test, Part B), as part of the OX-CHRONIC study, a longitudinal stroke cohort. Fatigue was assessed using the Fatigue Severity Scale. In a multiple linear regression analysis inclusive of above cognitive domains, only poorer executive functioning was associated with increased fatigue severity. This provides insight into the cognitive impairment profile of post-stroke fatigue long-term after stroke, with executive functioning deficits as the key hallmark.

Clinical features of vascular cognitive impairment

Vascular cognitive impairment (VCI) can occur in cerebrovascular disease of varying degree of severity, which requires further investigation.Objective: to identify specific features of attention deficit and executive function (EF) impairment in VCI and to determine the relationship between cognitive, neurological and radiological signs of the disease.Material and methods. The study involved 80 patients (51 with VCI – the main group and 29 healthy volunteers – the control group). All participants underwent clinical and neuropsychological examination and MRI of the brain. VCI was diagnosed according to 2014 VASCOG criteria. The neuropsychological examination included an assessment of the general cognitive function (MoCA test, MMSE); general EF (FAB, EXIT-25); episodic memory (12-word memory test and Benton Visual Retention Test); semantic memory (categorical association method); initiation and productivity of cognitive activity (literal associations); attention [TMT-A, Symbol-Digit Modalities Test (SDMT)]; cognitive flexibility (TMT-B); cognitive control (Stroop test).Results. As a result of the study, three subgroups of patients with VCI were identified: 1) predominantly attention deficit (AD); 2) AD and significant decrease in cognitive flexibility (CFD); 3) AD in combination with a significant cognitive control deficiency (CCD). The TMT-A and SDMT tests were significantly worse in all subgroups of VCI compared to the control group, with the worst SDMT score in subgroup 2. Subgroup 2 also had the longest time to complete the TMT-B test. Subgroup 3 was characterized by the worst Stroop test results, and uncontrolled arterial hypertension was more common in this group. Gait disturbances were significantly more frequent in subgroup 2, and increased reflexes of oral automatism and grasp reflex were observed in subgroup 3. White matter hyperintensity (WMH) was more pronounced in subgroup 2, and lacunar infarcts (LI) were more frequent in subgroup 3. Prevalence of LI and severity of WMH were lowest in subgroup 1.Conclusion. The main features of VCI are attention deficit and EF impairment, characteristics of EF disorders depend on the severity and type of vascular lesions of the brain. Progression of WMH is associated with more pronounced CFD and an increase in the number of LI is associated with CCD. There is a correlation between CFD and gait disturbances and between CCD and lack of primitive reflexes inhibition.

Contextual memory bias in emotional events: Neurobiological correlates and depression risk

BackgroundContextual memory loss of emotional events plays a critical role in depression psychopathology. Individuals with depression, clinical or subclinical, exhibit enhanced and impaired memory for emotionally negative stimuli and context in an event, respectively. This suggests that contextual encoding may fail because of attentional interference caused by concurrent negative stimuli, possibly leading to contextual memory loss as a depression risk. Amygdala–prefrontal connectivity and cortisol may underlie the mechanism; however, the relationships remain unknown. MethodsOne hundred twenty participants, including 34 with subclinical depression, underwent behavioral tasks, functional magnetic resonance imaging (fMRI) scans, and saliva collection. Encoding and 24 h later recollection performance of visuoperceptual/spatial/temporal context in a series of events, where fearful (vs. neutral) faces appeared, were measured via contextual memory tasks. Overgeneral autobiographical memory (OGM), a more remote form of contextual memory loss, was also assessed via the Autobiographical Memory Test. Amygdala connectivity was measured by fMRI during attentional interference by fearful (vs. neutral) faces to differentiate selective attention from encoding. Basal cortisol levels were assayed through saliva collected at encoding during the visit day and across 2 consecutive days in the following week (12 time points in total). We explored whether contextual memory encoding failure would explain depressive symptoms through OGM under possible moderation of amygdala connectivity and cortisol. ResultsIn individuals with subclinical depression compared to those without, fearful faces disturbed memory encoding of the visuoperceptual context rather than 24 h later recollection, while neutral faces in their temporal proximity contrastingly augmented it. The more the contextual memory encoding bias (fearful vs. neutral) intensified, the more the amygdala’s functional connectivity with the ventromedial prefrontal cortex (vmPFC) weakened. Higher total cortisol output tended to be correlated with poorer 24-h later recollection of the temporal context. Moderated mediation effects of the amygdala-vmPFC connectivity and cortisol were not significant; however, contextual encoding bias explained depressive symptoms through negatively valenced OGM. ConclusionsNegative stimuli appearing in an event might impair memory encoding of the visuoperceptual context under attentional interference, represented as weakened amygdala-vmPFC connectivity implicated in emotion-related attentional dysregulation. Conversely, negative stimuli might enhance temporally proximal visuoperceptual encoding after their disappearance. Contextual encoding bias could explain the overgeneralization (or lower coherence) of autobiographical memory and increase the risk of depression. The possible role of cortisol in recollecting the context of emotional events over time warrants further investigation.

A cross-cultural comparison of intrinsic and extrinsic motivational drives for learning.

Intrinsic motivational drives, like the autonomous feeling of control, and extrinsic motivational drives, like monetary reward, can benefit learning. Extensive research has focused on neurobiological and psychological factors that affect these drives, but our understanding of the sociocultural factors is limited. Here, we compared the effects of autonomy and rewards on episodic recognition memory between students from Dutch and Chinese universities. In an exploratory learning task, participants viewed partially obscured objects that they needed to subsequently remember. We independently manipulated autonomy, as volitional control over an exploration trajectory, as well as the chance to receive monetary rewards. The learning task was followed by memory tests for objects and locations. For both cultural groups, we found that participants learned better in autonomous than non-autonomous conditions. However, the beneficial effect of reward on memory performance was stronger for Chinese than for Dutch participants. By incorporating the sociocultural brain perspective, we discuss how differences in norms and values between Eastern and Western cultures can be integrated with the neurocognitive framework about dorsal lateral and ventral medial prefrontal cortex and dopaminergic reward modulations on learning and memory. These findings have important implications for understanding the neurocognitive mechanisms in which both autonomy and extrinsic rewards are commonly used to motivate students in the realm of education and urge more attention to investigate cultural differences in learning.

Voice biomarkers in middle and later adulthood as predictors of cognitive changes.

Prosody voice measures, especially jitter and shimmer, have been associated with cognitive impairment and hold potential as early indicators of risk for cognitive decline. Prior research suggests that voice measures assessed concurrently with longitudinal cognitive outcomes are associated with 10-year cognitive declines in middle-age and older adults from Midlife in the U.S. (MIDUS) study. Using a subsample from the same study, we expanded previous research to examine voice measures that were (1) collected 8 years before cognitive outcomes, (2) derived from narrative speech in logical memory tests instead of word list recall tests, and (3) independent of the cognitive outcomes. Multilevel analyses controlled for covariates of age, sex, education, neurological conditions, depressive symptoms, and chronic conditions. The results indicated that higher jitter and lower shimmer predicted greater 10-year declines in episodic memory and working memory. These findings extend previous research by highlighting prosody voice measures assessed 8 years earlier as predictors of subsequent cognitive declines over a decade.

Associations between accelerated forgetting, amyloid deposition and brain atrophy in older adults.

Accelerated long-term forgetting (ALF) is the phenomenon whereby material is retained normally over short intervals (e.g. minutes) but forgotten abnormally rapidly over longer periods (days or weeks). ALF may be an early marker of cognitive decline, but little is known about its relationships with preclinical Alzheimer's disease pathology, and how memory selectivity may influence which material is forgotten. We assessed ALF in 'Insight 46', a sub-study of the MRC National Survey of Health and Development (a population-based cohort born during one week in 1946) (n=429; 47% female; assessed aged ∼73 years). ALF assessment comprised visual and verbal memory tests: Complex Figure Drawing and the Face-Name Associative Memory Exam (FNAME). ALF scores were calculated as the percentage of material retained after 7 days, relative to 30 minutes. In 306 cognitively-normal participants, we investigated effects on ALF of β-amyloid pathology (quantified using 18F-Florbetapir-PET, classified as positive/negative) and whole-brain and hippocampal atrophy rate (quantified from serial T1-MRI over ∼2.4 years preceding the ALF assessment), as well as interactions between these pathologies. We categorized Complex Figure Drawing items as 'outline' or 'detail', to test our hypothesis that forgetting the outline of the structure would be more sensitive to the effect of brain pathologies. We also investigated associations between ALF and Subjective Cognitive Decline, measured with the MyCog questionnaire. Complex Figure 'outline' items were better retained than 'detail' items (mean retention over 7 days = 94% vs 72%). Amyloid-positive participants showed greater forgetting of the Complex Figure outline, compared to amyloid-negatives (90% vs 95%; P<0.01). There were interactions between amyloid pathology and cerebral atrophy, such that whole-brain and hippocampal atrophy predicted greater ALF on Complex Figure Drawing among amyloid-positives only (e.g. 1.9 percentage-points lower retention per ml/year of whole-brain atrophy [95% confidence intervals 0.5, 3.7]; P<0.05). Greater ALF on FNAME was associated with increased rate of hippocampal atrophy. ALF on Complex Figure Drawing also correlated with subjective cognitive decline (-0.45 percentage-points per MyCog point [-0.85, -0.05], P<0.05). These results provide evidence of associations between some measures of ALF and biomarkers of brain pathologies and subjective cognitive decline in cognitively-normal older adults. On Complex Figure Drawing, 'outline' items were better remembered than 'detail' items - illustrating the strategic role of memory selectivity - but 'outline' items were also relatively more vulnerable to ALF in individuals with amyloid pathology. Overall, our findings suggest that ALF may be a sensitive marker of cognitive changes in preclinical Alzheimer's disease.

Aerobic exercise prevents and improves cognitive dysfunction caused by morphine withdrawal via regulating endogenous opioid peptides in the brain.

Morphine withdrawal leads to serious cognitive deficits in which dynorphins are directly involved. Recently, exercise has been shown to prevent and improve cognition dysfunction in a variety of ways. Meanwhile, exercise can regulate the endogenous opioid peptides including dynorphins. However, it remains unclear whether exercise influences cognitive dysfunction caused by morphine withdrawal via dynorphins. In the current study, we investigate the physiological mechanism of exercise prevention and improvement aganist cognition dysfunction caused by morphine withdrawal. Male, adult C57BL/6 mice were randomly divided into 5 groups : Saline control (WT), exercise (EXE), morphine withdrawl (MW), exercise + morphine withdrawl (EMW), morphine withdrawl + exercise (MWE). We established aerobic exercise prevention/improvement models, and conducted behavioral tests including Open field test (OFT), Temporal order memory test (TOM) and Y-maze. Through Western Blotting and immunofluorescence staining, we detected endogenous opioid peptides in hippocampus and mPFC. Compared with MW group, EMW group and MWE group showed the same performance as WT group in TOM and Y-maze, with correct object recognition and memory ability. In Western Blotting and immunofluorescence staining experiments, it indicated that EMW group reduced the expression of PDYN and its fluorescence intensity in hippocampus; MWE group reduced the expression of OPRK1 and its fluorescence intensity in mPFC. Our data suggest that aerobic exercise can both prevent and improve cognitive dysfunction caused by acute morphine withdrawal via respectively down-regulating PDYN in the hippocampus and down-regulating OPRK1 in the mPFC. They may become new targets for drugs development in the future.

Effect of chronic alcohol exposure and single-prolonged stress on conditioned fear behavior

The present study investigated the impact of chronic intermittent ethanol (CIE) exposure and single-prolonged stress (SPS) on the acquisition of fear memories in both male and female Wistar rats. Adult rats were first subjected to CIE by vapor inhalation followed by SPS. Following a subsequent 8-day incubation period, the rats underwent a Pavlovian fear conditioning procedure (tone-shock pairings) followed by cued-tone extinction training, and then testing of extinction recall memory and fear renewal memory. In control animals that had not been exposed to either CIE or SPS, female rats exhibited significantly lower levels of freezing compared to male rats during tone-shock pairings. This lower level of freezing in female rats during conditioning was associated with an increased speed of movement compared to males. Also compared to males, female rats exhibited lower levels of fear extinction, recall, and renewal. Exposure to CIE, SPS, or CIE+SPS had no effect on freezing during the cued-conditioning, extinction, or extinction recall phases of the testing procedure in either sex. In fear renewal, CIE exposure decreased freezing in male but not female rats, while SPS increased freezing in female but not male rats. CIE exposure significantly reduced freezing during the fear renewal phase. Taken together, these results provide further evidence that male and female rats adopt different avoidance strategies for threat responding. These results also revealed that prior exposure to CIE, SPS, or CIE+SPS had minimal effects on threat responding using conditioned freezing as an indicator of fear responsivity.

Kelley's Paradox and strength skewness in research on unconscious mental processes.

A widely adopted approach in research on unconscious perception and cognition involves contrasting behavioral or neural responses to stimuli that have been presented to participants (e.g., old items in a memory test) against those that have not (e.g., new items), and which participants do not discriminate in their conscious reports. We demonstrate that such contrasts do not license inferences about unconscious processing, for two reasons. One is Kelley's Paradox, a statistical phenomenon caused by regression to the mean. In the inevitable presence of measurement error, true awareness of the contrasted stimuli is not equal. The second is a consequence, within the framework of Signal Detection Theory, of unequal skewness in the strengths of target and nontarget items. The fallacious reasoning that underlies the employment of this contrast methodology is illustrated through both computational simulations and formal analysis, and its prevalence is documented in a narrative literature review. Additionally, a recognition memory experiment is reported which tests and confirms a prediction of our analysis of the contrast methodology and corroborates the susceptibility of this method to artifacts attributable to Kelley's Paradox and strength skewness. This work challenges the validity of conclusions drawn from this popular analytic approach.

Isolated during adolescence: long-term impact on social behavior, pain sensitivity, and the oxytocin system in male and female rats

BackgroundAdolescent social isolation (ASI) has profound long-term effects on behavioral and neural development. Despite this, the specific long-term impact of ASI during different adolescent stages and across sexes remain underexplored.MethodsOur study addresses this gap by examining the effects of early- and late- adolescent social isolation on both male and female rats. Rats were either isolated (or group-housed) starting from PD 21 (early) or PD 42 (late) for three weeks and then rehoused into groups. In adulthood (PD 90), rats underwent a battery of tests: elevated plus-maze, open field, novel object recognition, social interaction and social recognition memory and hotplate tests. Finally, we analyzed oxytocin receptor binding in several regions in the brains of a second cohort of rats.ResultsBoth, male and female rats from the late adolescent social isolation (LASI) groups spent significantly less time interacting in the social interaction test. Additionally, we observed a general decrease in social recognition memory regardless of sex. Both male ASI groups demonstrated heightened thermal pain sensitivity, while the opposite was observed in early adolescent social isolation (EASI) female rats. In the brain, we observed changes in oxytocin receptor (OTR) binding in the paraventricular nucleus of the hypothalamus (PVN) and paraventricular nucleus of the thalamus (PVT) and central amygdala (CeA) with the largest changes in EASI and LASI female rats.ConclusionOur model demonstrates long-lasting alterations on behavior and oxytocin receptor binding levels following ASI providing insights into the long-term effects of ASI in a time- and sex-specific manner.

Plasma neurofilament heavy chain is a prognostic biomarker for the development of severe epilepsy after experimental traumatic brain injury.

This study was undertaken to test whether the postinjury plasma concentration of phosphorylated neurofilament heavy chain (pNF-H), a marker of axonal injury, is a prognostic biomarker for the development of posttraumatic epilepsy. Tail vein plasma was sampled 48 h after traumatic brain injury (TBI) from 143 rats (10 naïve, 21 controls, 112 with lateral fluid percussion injury) to quantify pNF-H by enzyme-linked immunosorbent assay. During the 6th postinjury month, rats underwent 30 days of continuous video-electroencephalographic monitoring to detect unprovoked seizures and evaluate epilepsy severity. Somatomotor (composite neuroscore) and spatial memory (Morris water maze) testing and quantitative T2 magnetic resonance imaging were performed to assess comorbidities and lesion severity. Of the 112 TBI rats, 25% (28/112) developed epilepsy (TBI+) and 75% (84/112) did not (TBI-). Plasma pNF-H concentrations were higher in TBI+ rats than in TBI- rats (p < .05). Receiver operating characteristic curve analysis indicated that plasma pNF-H concentration distinguished TBI+ rats from TBI- rats (area under the curve [AUC] = .647, p < .05). Differentiation was stronger when comparing TBI+ rats exhibiting severe epilepsy (≥3 seizures/month) with all other TBI rats (AUC = .732, p < .01). Plasma pNF-H concentration on day 2 (D2) distinguished TBI+ rats with seizure clusters from other TBI rats (AUC = .732, p < .05). Higher plasma pNF-H concentration on D2 after TBI correlated with lower neuroscores on D2 (p < .001), D6 (p < .001), and D14 (p < .01). Higher pNF-H concentration on D2 correlated with greater T2 signal abnormality volume on D2 (p < .001) and D7 (p < .01) and larger cortical lesion area on D182 (p < .01). Plasma pNF-H concentration on D2 did not correlate with Morris water maze performance on D37-D39. Plasma pNF-H is a promising clinically translatable prognostic biomarker for the development of posttraumatic epilepsy with frequent seizures or seizure clusters.